OP THE PARAFFINS AND THEIR MONOHALOGEN DERIVATIVES. 
27 
previously described. These had a range of pressures from 179 millims. to 453 millims.> 
and the results are given in the first three columns of Table XIII. 
To extend the values to the higher pressures the following method was adopted. 
From the curve in fig. 11 the values oipvjt were taken for the pressures at which the 
absolute determinations were made. These are given in the fourth column of the 
table, and should give a constant if multiplied by the numbers in the third column. 
The fifth colmnn gives these products. The extreme variation is one part in a thousand, 
and the numbers do not increase progressively in either direction, which shows the 
consistency of the two series, and is a test of the degree of accuracy reached in the 
vapour density determinations. 
Table XIII. 
p. 
t 
P- 
pv 
pVf) 
t + 27S' 
t + 273 
179 
13-6 
2-244 
3667 
8229 
242 
10-2 
2-251 
3655 
8227 
301 
13 
2-256 
3644 
8221 
329 
13-5 
2-262 
3637 
8227 
357 
15 
2-265 
3631 
8224 
453 
12-8 
2-276 
3615 
8228 
]\[eau . 
8226 
To find the best value of the constant of thepy curve, the mean of the six values 
of pvpjt was taken, and this mean divided by the ordinate of the curve of fig. 11 for 
any pressure gives the S.G. of the vapour at that pressure. 
Using the values so obtained, the following table gives the final results for the 
ratio of the specific heats, the columns having the same meanings as in the case of the 
previous gases. 
Table XIV. 
P- 
t. 
1 . 
V. 
!>■ 
1 4- 
p {dv) ■ 
7- 
200 
12-8 
29-34 
48-3-2 
2-245 
1.012 
1-180 
205 
15-4 
29-48 
48-54 
2-245 
1-012 
1-180 
285 
14-2 
29-41 
48-45 
2-255 
1-016 
1-189 
295 
15 
29-31 
48-49 
2-257 
1-016 
1-180 
400 
16-4 
29-49 
48-75 
2-270 
1-019 
1-191 
400 
17-8 
29-49 
48-81 
2-270 
1-019 
1-188 
410 
15-5 
29-31 
48-61 
2-271 
1-019 
1-184 
560 
16-5 
29-21 
48 61 
2-290 
1-025 
1-193 
610 
17-1 
29-22 
48-72 
2-294 
1-025 
1-190 
630 
16-4 
29-15 
48-61 
2-297 
1-025 
1-192 
Mean . . 
1-187 
E 2 
